The present invention relates to a fluid injection system and, more particularly, to a blocking condition detection device for a fluid injection system, including a medical system.
A conventional blocking condition detection device for a fluid injection system is disclosed in U.S. Pat. No. 4,369,780, issued Jan. 25, 1983, entitled "BLOCKING CONDITION DETECTION DEVICE IN A MEDICAL FLUID INJECTION SYSTEM", granted to the same applicant. The essence of this patent is as follows:
A medical fluid injection system includes a flexible conduit and a rotor for supplying a pressurized medical fluid to the human body through the flexible conduit. A blocking condition detection unit is provided for detecting an abnormal blocking condition of the flexible conduit. The blocking condition detection unit includes a supporting member for supporting the flexible conduit in a manner that the section of the flexible conduit is forced to show a rectangular configuration. A rod is slidably disposed through the supporting member so that one end of the rod makes contact with the flexible conduit. When an abnormal blocking condition occurs in the flexible conduit, the flexible conduit held by the supporting member expands to depress and shift the rod. The created movement of the rod is detected by a microswitch, whereby the rotation of the rotor is interrupted.
The system of this patent shows a high degree of reliability. The disclosure of this patent is incorporated herein by reference.
As another aspect of a blocking condition detection device for a fluid injection system, attention can be directed to the positive usage of the creep feature of the flexible conduit to detect a small fluid-blocking pressure, in which the diameter of the flexible conduit can change.